Preparation Of Photocatalytic Self-cleaning Micro/nanofibrous Membrane And Study On Oil-water Separation Performance

The large amount of oily wastewater poses a serious threat to human health,also has adverse impact on nature.Various water treatment technologies and methods(especially membrane separation technologies)have been developed.How to improve the separation performance of filtration membrane is still a key challenge that restrict the preparation of high-performance separation membrane.To solve the problem,based on the structure and performance advantages of nanofibrous membrane and microfibers membrane,the high-performance micro/nano fibrous gradient composite membrane were designed and prepared.It provides new ideas for the application of micro/nano-materials in the field of filtration.These research contents are as follows:Polyvinylidene fluoride/titanium dioxide(PVDF/Ti O₂)nanofibrous membrane was prepared by blending electrospinning technology,and the influence of different Ti O₂ additions on the performance of PVDF/Ti O₂ nanofibrous membrane was emphatically investigated,providing theoretical basis and data support for the subsequent preparation of special-shaped structural membrane.When the Ti O₂ content was 12%,97%rhodamine B was degraded and the photocatalytic rate was 10 times that of pure PVDF membrane.In order to further improve the performance of nanofibrous membrane.The special advantage of electrospinning technology was used to construct the special-shaped structures nanofibrous membrane successfully.M-PVDF/Ti O₂ nano-membrane with papillae structure was successfully constructed via adjusting the concentration of spinning solution,and the underwater oleophobic PDA-M-PVDF/Ti O₂ membrane was prepared by in-situ polymerization of dopamine and separation efficiency of oil/water mixture up to 99%and water flux of 1389±67 L·m^-2·h^-1.In order to improve the separation efficiency and water flux of the membrane,the poly(N-isopropylacrylamide)/polyacrylonitrile/Ti O₂(PNIPAM/PAN/Ti O₂)membrane with overlapped structure was prepared by the blending electrospinning technology of hydrophilic polymer.The water flux of the membrane is 7713±324 L·m^-2·h^-1.The separation efficiency of the membrane is 99.2%.Polypropylene/Ti O₂(PP/Ti O₂)microfiber membrane were successfully prepared by melting blending and melt-blown method.By adjusting the melt-blown process parameters,the melt-blown PP membrane with different basis weights was prepared,and the polydopamine/3-aminopropyltriethoxysilane@PP(PDA/APTES@PP)microfiber membrane with hydrophilic-underwater oleophobic prepared via in-situ polymerization technology.When the polymerization time was 12 h and the addition ratio of DA and APTES was 1:2,the DA/APTES-1/2@PP membrane had the best performance,and the water flux was 147424±7112 L·m^-2·h^-1.The membrane can achieve high permeation flux and good separation efficiency for oil-water mixture just under the gravity.Based on the structural and performance advantages of nanofibrous membrane and microfiber membrane.The PP/low-melt point polyester(PP/LPET)microfiber membrane and electrospinning nanofibrous membrane were compounded to prepare the micro/nanofibrous gradient composite membrane through needle-hot pressing reinforcement,and explore the performance of the composite membrane.It provides a feasible solution to overcome the great filtration resistance of electrospinning membrane,and provides a new idea for the preparation of low cost and highly performance composite membrane.Using the response surface design method,an empirical equation was established to optimize the process parameters of the nanofibrous membrane and micro/nanofibrous gradient composite membrane,respectively.The gradient mechanism is analyzed to provide guidance for actual industrial production.